Acoustic panels



March 3, 1970 R. L. CHARPENTIER 3,493,405

1 I ACOUSTIC PANELS Filed Dec. 18, 19s? 4 Sheets-Sheet 1 N VE' N TOR Aoesre L. CH4 RPEN TIER ATTOKNE Y6 March 3, 1970 R. L. CHARPENTIER 3,498,405

ACOUSTIC PANELS Filed Dec. 18, 1967 4 Sheets-Sheet 2 IN VEN TOR R0 5? L. C/memsw r1512 ATTORNEYS March 3;, 1970 R. CHARPENTIER 3,498,405

ACOUSTIC PANELS Filed Dec. '18, 1967 4 Sheets-Sheet 5 F79- 4 I 9 5 l l5 l3 l6) IN VENTOR A 065? L. CunePavT/EE .4 TTOR/VEYS March 3, 1970 R. 1.. CHARPENTIER 3,498,405

ACOUSTIC PANELS 4 Sheets-Sheet 4 Filed Dec. 18, 1967 k 8% 8mm 3% QQM QMN wmx m ME IN VE N TOR Rose-R L. Cl-IARPEN r/ER BY ATTORNEYS United States Patent US. Cl. 18133 17 Claims ABSTRACT OF THE DISCLOSURE A sound insulating panel of foamed phenolic resin has one face provided with a foil having projection in the form of truncated pyramids or elongate ridges of trapezoidal cross-section. The foil is secured to the foam material but is spaced over a part of its extent to form an acoustic diaphragm.

This invention relates to a panel intended particularly to constitute a sound-insulating covering for the ceiling and walls of a building.

According to the present invention there is provided a sound insulating panel comprising a sheet of a material capable of absorbing sound waves and a relatively flexible foil having on its external face a plurality of projections shaped and arranged to reduce the reflection of sound waves, this foil being mounted below the sheet and connected thereto with some freedom of movement in order to constitute over a part at least of its extent an acoustic diaphragm.

The absorbent material of the sheet is a foamed material, preferably phenolic, having at least 20% of its pores open.

The projections are formed by pressing, preferably in vacuum, in the relatively flexible foil.

The said projections preferably have the form, either of the truncated pyramid which has a square base, or a trapezoidal section prism.

The connection of the foil with the sheet is effected by means of at least one spot of glue. It can also be effected by means of at least two pointed members, such as clips, hooks or other members, engaging through an edge of the said foil into the edge of the said sheet.

The covering comprises over its whole surface as many panels with holes in the crests of the projections as those without holes.

Moreover, each panel can cooperate with at least one magnetic securing member which, preferably, is constructed as described.

A covering provided by means of such panels possesses good sound-insulating properties. In particular, the variation of its acoustic absorption coefficient is substantially more satisfactory in the range of audible frequencies than those of existing panels.

Moreover, the purchase cost of a panel is reasonable and the overall cost of installation far less than that of previously proposed arrangements, assuming that furthermore the support structure is simpler to assemble and to transport, because the mounting of the panels is very rapid and gives rise to no difiiculty, that the labour to be employed to this end may be without special qualificationl Moreover, these panels are easily removed. On account of this all the parts situated above them, such as conduits, cables or other items, are accessible and can without difliculty be repaired and replaced. The cleaning of these panels can also be effected at ground level under easier conditions.

Finally, the covering thus provided has a pleasing appearance capable of harmonising with various decorating styles of buildings.

Embodiments of panels in accordance with the invention, will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a partial perspective view showing a first embodiment of the panel in accordance with the invention;

FIG. 2 is another partial perspective view illustrating a second embodiment;

FIGS. 3 and 3a are fragmentary sections on the line IIIIII of FIGURE 1 showing two methods of connection of the foil with projections with the foam sheet;

FIG. 4 is a partial section illustrating another connection method;

FIGS. 5 to 7 are similar views to FIGURE 4 relating to three magnetic securing methods of panels on the supporting framework;

FIG. 8 is a partial plan view from below of a covering showing in use panels with holes and panels without holes, and

FIG. 9 is a graph representing the variation of the coeflicient of acoustic absorption; alpha Sabine percent being given as the ordinate with respect to sound frequencies; F given as abscissa, for panels without holes, panels with holes and a distribution in equal parts of the latter.

As is shown in FIGS. 1 and '2, the panel 1 in accordance with the invention comprises a sheet 2 which can be of any material capable of absorbing sound waves. Preferably, it is the phenolic foam since this, besides being an excellent sound and thermal insulator, is non-inflamable and chemically inert, that is to say non-corrosive. In any case, this foam has at least 20% of its pores open.

The sheet 1 also comprises a relatively flexible foil 3 which is provided on its external face with projections 4 (FIG. 1) or 5 (FIG. 2) shaped and distributed in order to prevent or at least reduce the reflection of sound waves.

According to the embodiment illustrated in FIG. 1, the projections 4 each has the form of a truncated pyramid with a square base, of which the lateral faces converge downwardly.

According to the embodiment illustrated by FIGURE 2, the projections 5 have the form of a trapezoidal section prism of which the converging faces also converge downwardly. These prismatic projections extend over substantially the whole of the length of the sheet 3 and are parallel to one another. On this account, the panel of FIGURE 2 is easier to clean than that of FIGURE 1.

In any case, in the one case as in the other, the projections 4 and 5 may advantageously be formed by shaping of the foil, preferably under vacuum. This foil may be constituted by polyvinyl chloride or any other appro priate synthetic-resin material.

It is important to note that the foil 3 is mounted below the sheet 2 and freely connected to the latter in such a manner as to constitute over a part at least of its extent an acoustic diaphragm.

Furthermore, holes 6 (FIG. 8) may be provided in the crests of certain or in all of the projections 4 and 5.

Consequently, several acoustic effects are combined; anti-reflection by the projections 4 and 5, bending and transmission by the foil 3 forming a diaphragm, absorption by the foam sheet 2., directional transmission of certain frequencies by the holes 6 etc.

With regard to the connection of the sheet 3 with the sheet 2, several embodiments are envisaged.

According to a first embodiment, the foil 3 has an edge 7 normal thereto (FIG. 3) of small height which is forced onto the sheet 2 in order to grip it. Alternatively, this edge is freely engaged and is glued on to the edge 8 of the said sheet.

According to a modification illustrated in FIG. 3a the edge 7 of the sheet 3 has a re-entrant part 7a which is thus in dove-tailed relationship. The reentrant part 7a may be provided over the whole periphery of the edge 7 and over its whole height. Nevertheless, there would be no difficulty in limiting the re-entrant part to extend only along one or several lengths. The re-entrant part 7a is normally engaged in a groove 8a provided in the edge 8 of the sheet 2. If the part 7a is plane and inclined, the groove 8a has a V-section. This is the embodiment which is preferred, but it is clearly evident that other shapes can be adopted.

During the construction of a panel 1, it is sufficient thus to engage the part 7a of the edge into the groove 8a and then locking is effected, a foil 3 is in contact with the corresponding face of the sheet 2. But this contact is effected without any connection, so that the foil 3 can act as an acoutic diaphragm. Because of the slope of the part 7a and of the groove 8a, the foil 3 tends to remain in contact at its periphery with the sheet 2. The re-entrant part 7a can be inserted when heated in the groove 8a. But, because the foil 3 is relatively flexible, the part 7a can also be engaged in the cold by elastic deformation.

Furthermore, the edge 7-7a can be continuous or even solutions of continuity may be provided over the length in order to facilitate its engagement in the groove. These continuous solutions can be created by means of slits cut in the edge 7, following perpendicular directions to the lines of the sheet 3 or inclined thereto. According to a second embodiment of connection means, gluing spots appropriately separated are provided between the faces in contact of the foil 3 and of the sheet 2.

It may be advantageous to control exactly the effect of the acoustic diaphragm and not to render this effect dependent upon the securing requirements. In this case, the foil 3 is mounted on the sheet 2 by means illustrated in FIGURE 3a; the gluing spots are thus used only to limit the surface of the diaphragm and it is only as accessories that they participate in the securing. On account of this, it is possible to provide the foil 3 constituting a diaphragm over its full extent or a part only of the latter or that it forms several contiguous diaphragms.

According to a third embodiment (FIG. 4), the foil 3 is rigid with one edge 9 of greater height than the edge 7 and pointed members, as for example the staples of U-shape 10, are driven through the said edge 9 into the edge 8 of the sheet 2.

It is clearly evident that in order to provide the diaphragm referred to, the foil 3 may be applied without clearance (FIG. 3) by its parts bordering the hollow projections 4 and 5, against the sheet 2. But, a small clearance can also be provided between them.

The panel 1 in accordance with the invention comprises furthermore, in combination with the sheet 2 and the foil 3 freely assembled together, at least one magnetic securing member.

In the example illustrated in FIGURES and 6, it comprises a small plate 11 formed as a corner, rigid with at least one fastener 12 and cooperating with at least one staple 13, this small plate carrying a magnetic attraction unit 14 capable of being applied, for securing the panel 1, against the carrying or supporting framework of steel on which the said small plate is centered by means of at least One tongue 15.

According to a first securing method illustrated in FIG. 5, the fasteners 12 are engaged perpendicularly in the edge 8 of the sheet 2 and the staple 13 is introduced in an inclined fashion into the hidden face 16 of the sheet 2. In other words, the sheet 2 is secured magnetically below the supporting framework and the foil 2 is freely assembled beneath the sheet, in particular by spots of glue.

According to a second securing method illustrated in FIGURE 6, the edge 9 has, opposite the small plates 11, clearances 17 set back substantially by the thickness of the a e The fasteners 12 are t en eng g d, through the edge 9 in the zone of the clearances, in the edge 8 of the sheet 2 and the staples 13 are introduced in an inclined fashion into the hidden face 16 of the sheet 2. In other words, the fasteners 12 effect the free connection of the foil 3 with the sheet 2 and securing of this assembly constituting the panel 1, below the supporting framework through the intermediary of the magnetic attraction units 14.

The magnetic securing member or members hereinbefore referred to may be other than that shown in FIG- URES 5 and 6. In particular, they may be constituted as shown in FIGURE 7, by strips 18, of a flexible material containing an alloy of magnetic material. These strips are disposed along two opposite sides of the panel or even along the four sides thereof. They are glued on the hidden face 16 of the sheet 2 and are arranged to cooperate with the supporting framework of steel.

In order to demonstrate the acoustic qualities of this panel, the results of tests are shown graphically in FIGURE 9.

These tests were carried out on a covering A constituted by panels 1 such as illustrated in FIGURE 5 These panels comprised in this non-limiting example:

A sheet 2 of 15 millimeters thickness and of 585 millimeters along the sides of foam phenolic resin, having 20% of its pores open.

A foil 3 of polyvinyl chloride of A of a millimeter thickness of which the pyramidial projections 4 had sides at the base of 12 mm., sides at the peak of 4 mm. and 4 mm. in height, the spacing of the projections being 16 millimeters in both directions.

The foil 3 was applied without clearance against the sheet 2 and the connection between them was provided by five spots of glue located at the four corners and at the centre, as well as between the edge 7 and the edge 8 by a film of glue.

Four magnetic securing members 11 to 15 mounted at the extremities of two opposed edges of each panel.

The tests were also carried out on a covering B constituted by panels 1a. These panels 1a were identical to those 1 of the covering A, but they had holes 6 in the crests of all their projections 4.

.Tests were finally carried out on a covering C constituted as many of the panels 1 as of the panels 1a (FIGURE 8).

Measurements of the coefficient of absorption alpha Sabine percent of coverings A, B and C were effected with a Kundts tube for various ranges of frequency from l25 cycles per second to 4000 cycles per second.

The graph of FIGURE 9 shows the variation in the coefficient of absorption.

for the covering A on the curve 19 for the covering B on the curve 20 for the covering C on the curve 21.

It is of little value to comment on these curves, because it is evident that the embodiment C is particularly advantageous for sound insulation of commercial buildings, industrial buildings or dwellings.

I claim:

1. A sound insulating panel, comprising: a substantially rigid sheet of porous, foamed phenolic resin capable of absorbing sound waves having an external and an internal face; an acoustic diaphragm covering the external face of the porous sheet formed of a sheet of relatively flexible foil having a plurality of closely spaced, truncated projections integral therewith extending outwardly on its external face arranged to reduce the reflection of sound waves; the foil sheet being disposed with its internal face contiguous with and in free, non-connected engagement with the external face of the porous sheet; means connecting the diaphragm to the porous sheet; said means comprising a peripheral edge on said foil sheet integral therewith engaging and gripping the peripheral edges of: e porous sheet and at east one magne ized member carried by the internal face of the porous sheet capable of securing the panel to a support of magnetic material.

2. A sound insulating panel according to claim 1 in which the external face of the porous sheet is planar; at least of the pores of the porous sheet are open; the crests of at least some of the projections have apertures formed therein; the projections provided cavities for deflecting sound waves; a spot of glue connects the peripheral edges of the porous sheet and the foil sheet; the magnetized member is a strip of flexible material containing an alloy of magnetic material adhesively secured along at least two opposite sides of the internal face of the porous sheet.

3. A sound insulating panel according to claim 1, in which a spot of glue is located between the external face of the porous sheet and the internal face of the foil sheet and connects them together at the glue spot thereby forming a plurality of contiguous diaphragms.

4. A panel according to claim 1, wherein the absorbent material of the sheet is a foam, having at least 20% of its pores open.

5. A panel according to claim 1, wherein those parts of the foil which border the projections bear against the sheet of the absorbent material, the internal cavities of the said projections being free of this material.

6. A panel according to claim 1, wherein a small clearance is provided between those parts of the foil bounding the projections and the opposing face of the sheet of absorbent material.

7. A panel according to claim 1, wherein the projections have the form of a truncated pyramid with a square base.

8. A panel according to claim 1, wherein the projections are in the form of a trapezoidal section prisms, and extend over the whole length of the panel.

9. A panel according to claim 1, wherein the connection means comprises at least one spot of glue.

10. A panel according to claim 1, wherein connection means includes an inturned edge of the foil,

said sheet having a groove along at least one edge thereof, and the inturned edge engages in said groove.

11. A panel according to claim 1, wherein the inturned edge of the foil is continuous.

12. A panel according to claim 1, wherein the edge of the foil is separated at several parts by slits extending substantially perpendicular to the edges of the foil.

13. A panel according to claim 1, wherein said connection means comprises,

at least two pointed members, engaged transversely in an edge of the said foil and into the edge of the said sheet.

14. A panel according to claim 1, wherein the crests of at least some of the projections have apertures therein.

15. A panel according to claim 1, wherein each magnetized securing member comprises a small plate, and fasteners on said small plate,

said fasteners being engaged directly in the edge of the sheet of absorbent material.

16. A panel according to claim 1, wherein the mag- .netized securing member comprises a plate, and

fasteners engaged in the edge of the sheet of absorbent material through an opening in the edge of the foil,

said opening being offset with respect to this edge substantially by the thickness of the small plate.

17. A panel according to claim 1, wherein the magnetized securing member is constituted by a strip of flexible material containing a powdered magnetised metallic alloy, this strip being rigid with the sheet of absorbent material.

References Cited UNITED STATES PATENTS 2,045,311 6/1936 Roos et al. 2,060,241 11/ 193 6 Prudden. 2,373,401 4/1945 King. 3,174,580 3/1965 Schulz et al. 3,243,374 3/1966 Gillard 18133 XR FOREIGN PATENTS 1,163,584 4/1958 France.

328,974 5/ 1958 Switzerland.

ROBERT S. WARD, 111., Primary Examiner US. Cl. X.R. 181-30 

